Molecular analysis of PROP1, POU1F1, LHX3, and HESX1 in Turkish patients with combined pituitary hormone deficiency: a multicenter study

Comparison of clinical characteristics of a pediatric cohort with combined pituitary hormone deficiency caused by mutation of the PROP1 gene or of other origins

The most commonly identified genetic cause of combined pituitary hormone deficiency (CPHD) is PROP1 gene mutations. The aim of the study was to compare selected clinical features of patients with CPHD caused by variants of the PROP1 gene (CPHD-PROP1) and patients with inborn CPHD of other etiology (CPHD-nonPROP1).

MATERIAL AND METHODS

The retrospective analysis included childhood medical records of 74 patients (32 female) with CPHD, including 43 patients (23 female) with the mutation in the PROP1 gene.

RESULTS

Patients with CPHD-PROP1 compared to the CPHD-nonPROP1 presented with the following: significantly higher median birth weight (0.21 vs. - 0.29 SDS, p = 0.019), lower growth velocity within 3 years preceding growth hormone administration (- 2.7 vs. - 0.8 SDS, p < 0.001), higher mean maximal blood concentration of growth hormone within the stimulation process (1.2 vs. 1.08 ng/mL, p = 0.003), lower TSH (1.8 vs. 2.4 µIU/mL, p < 0.001), significantly lower prolactin concentrations (128 vs. 416.3 µIU/mL, p < 0.001), and less frequent typical signs of hypogonadism at birth in boys (n = 6; 30% vs. n = 12, 54%, p < 0.001). Secondary adrenal insufficiency was less frequent in CPHD-PROP1 (20 vs. 25 cases, p = 0.006) and occurred at a later age (13.4 vs. 10.4 years). MRI of the pituitary gland in CPHD-PROP1 revealed a small pituitary gland (21 cases), pituitary gland enlargement (eight cases), and one pituitary stalk interruption and posterior lobe ectopy, while it was normal in nine cases.

CONCLUSION

Patients with the PROP1 mutations present a clinical picture significantly different from that of other forms of congenital hypopituitarism. Certain specific clinical results may lead to the successful identification of children requiring diagnostics for the PROP1 gene mutation.

Genetic diagnosis of congenital hypopituitarism in Turkish patients by a target gene panel: novel pathogenic variants in GHRHR, GLI2, LHX4 and POU1F1 genes

Objective

Congenital hypopituitarism (CH) is a rare disease characterized by one or more hormone deficiencies of the pituitary gland. To date, many genes have been associated with CH. In this study, we identified the allelic variant spectrum of 11 causative genes in Turkish patients with CH.

Materials and methods

This study included 47 patients [21 girls (44.6%) and 26 boys (55.4%)] from 45 families. To identify the genetic etiology, we screened 11 candidate genes associated with CH using next-generation sequencing. To confirm and detect the status of the specific familial variant in relatives, Sanger sequencing was also performed.

Results

We identified 12 possible pathogenic variants in GHRHR, GH1, GLI2, PROP-1, POU1F1, and LHX4 in 11 patients (23.4%), of which six were novel variants: two in GHRHR, two in POU1F1, one in GLI2, and one in LHX4. In all patients, these variants were most frequently found in GLI2, followed by PROP-1 and GHRHR.

Conclusion

Genetic causes were determined in only 23.4% of all patients with CH and 63% of molecularly diagnosed patients (7/11) from consanguineous families. Despite advances in genetics, we were unable to identify the genetic etiology of most patients with CH, suggesting the effect of unknown genes or environmental factors. More genetic studies are necessary to understand the etiology of CH.

POU1F1/Pou1f1 c.143-83A > G Variant Disrupts the Branch Site in Pre-mRNA and Leads to Dwarfism

POU Class 1 Homeobox1 (POU1F1/Pou1f1) is a well-established pituitary-specific transcription factor, and causes, when mutated, combined pituitary hormone deficiency in humans and mice. POU1F1/Pou1f1 has 2 isoforms: the alpha and beta isoforms. Recently, pathogenic variants in the unique coding region of the beta isoform (beta domain) and the intron near the exon-intron boundary for the beta domain were reported, although their functional consequences remain obscure. In this study, we generated mice carrying the Pou1f1 c.143-83A>G substitution that recapitulates the human intronic variant near the exon-intron boundary for the beta domain. Homozygous mice showed postnatal growth failure, with an average body weight that was 35% of wild-type littermates at 12 weeks, which was accompanied by anterior pituitary hypoplasia and deficiency of circulating insulin-like growth factor 1 and thyroxine. The results of RNA-seq analysis of the pituitary gland were consistent with reduction of somatotrophs, and this was confirmed immunohistochemically. Reverse transcription polymerase chain reaction of pituitary Pou1f1 mRNA showed abnormal splicing in homozygous mice, with a decrease in the alpha isoform, an increase in the beta isoform, and the emergence of the exon-skipped transcript. We further characterized artificial variants in or near the beta domain, which were candidate positions of the branch site in pre-mRNA, using cultured cell-basis analysis and found that only c.143-83A>G produced transcripts similar to the mice model. Our report is the first to show that the c.143-83A>G variant leads to splicing disruption and causes morphological and functional abnormalities in the pituitary gland. Furthermore, our mice will contribute understanding the role of POU1F1/Pou1f1 transcripts in pituitary development.

Novel compound heterozygous variants in the LHX3 gene caused combined pituitary hormone deficiency: A case report

BACKGROUND

Combined pituitary hormone deficiency 3 (CPHD3; OMIM: 221750) is caused by mutations within the LHX3 gene (OMIM: 600577), which located on the subtelomeric region of chromosome 9 at band 9q34.3, has seven coding exons and six introns. LIM homeobox (LHX) 3 protein is the key regulator of pituitary development in fetal life.

CASE SUMMARY

We have diagnosed and treate an 11-year-old boy with combined pituitary hormone deficiency (CPHD). The main clinical manifestations were pituitary hormone deficiency, hydrocele of the tunica vaginalis, pituitary dwarfism, gonadal dysplasia, micropenis, clonic convulsion, and mild facial dysmorphic features. We collected peripheral blood from the patient, the patient's older brother, as well as their parents, and sequenced them by using high-throughput whole-exosome sequencing, which was verified by Sanger sequencing. The results showed that there were two compound heterozygous variants of c.613G>C (p.V205L) and c.220T>C (p.C74R) in the LHX3 gene. c.613G>C (p.V205L) was inherited from his mother and c.220T>C (p.C74R) from his father. His brother also has both variants and symptoms.

CONCLUSION

This study reported ununreported genetic mutations of LHX3, and recorded the treatment process of the patients, providing data for the diagnosis and treatment of CPHD.

Presentation and diagnosis of childhood-onset combined pituitary hormone deficiency: A single center experience from over 30 years

BACKGROUND

Childhood-onset combined pituitary hormone deficiency (CPHD) has a wide spectrum of etiologies and genetic causes for congenital disease. We aimed to describe the clinical spectrum and genetic etiologies of CPHD in a single tertiary center and estimate the population-level incidence of congenital CPHD.

METHODS

The retrospective clinical cohort comprised 124 CPHD patients (48 with congenital CPHD) treated at the Helsinki University Hospital (HUH) Children's Hospital between 1985 and 2018. Clinical data were collected from the patient charts. Whole exome sequencing was performed in 21 patients with congenital CPHD of unknown etiology.

FINDINGS

The majority (61%;76/124) of the patients had acquired CPHD, most frequently due to craniopharyngiomas and gliomas. The estimated incidence of congenital CPHD was 1/16 000 (95%CI, 1/11 000-1/24 000). The clinical presentation of congenital CPHD in infancy included prolonged/severe neonatal hypoglycaemia, prolonged jaundice, and/or micropenis/bilateral cryptorchidism in 23 (66%) patients; despite these clinical cues, only 76% of them were referred to endocrine investigations during the first year of life. The median delay between the first violation of the growth screening rules and the initiation of GH Rx treatment among all congenital CPHD patients was 2·2 years, interquartile range 1·2-3·7 years. Seven patients harbored pathogenic variants in PROP1, SOX3, TBC1D32, OTX2, and SOX2, and one patient carried a likely pathogenic variant in SHH (c.676G>A, p.(Ala226Thr)).

INTERPRETATION

Our study suggests that congenital CPHD can occur in 1/16 000 children, and that patients frequently exhibit neonatal cues of hypopituitarism and early height growth deflection. These results need to be corroborated in future studies and might inform clinical practice.

FUNDING

Päivikki and Sakari Sohlberg Foundation, Biomedicum Helsinki Foundation, and Emil Aaltonen Foundation research grants.

A Novel Splice-Site Deletion in the POU1F1 Gene Causes Combined Pituitary Hormone Deficiency in Multiple Sudanese Pedigrees

Pathogenic variants within the gene encoding the pituitary-specific transcription factor, POU class 1 homeobox 1 (POU1F1), are associated with combined pituitary hormone deficiency (CPHD), including growth hormone, prolactin, and thyrotropin stimulating hormone deficiencies. The aim of the study was to identify genetic aetiology in 10 subjects with CPHD from four consanguineous Sudanese families. Medical history, as well as hormonal and radiological information, was obtained from participants’ medical records. Targeted genetic analysis of the POU1F1 gene was performed in two pedigrees with a typical combination of pituitary deficiencies, using Sanger sequencing, and whole-exome sequencing was performed in the other two pedigrees, where hypocortisolism and additional neurologic phenotypes were also initially diagnosed. In POU1F1 gene (NM_001122757.2) a novel homozygous splice-site deletion—namely, c.744-5_749del—was identified in all 10 tested affected family members as a cause of CPHD. Apart from typical pituitary hormonal deficiencies, most patients had delayed but spontaneous puberty; however, one female had precocious puberty. Severe post-meningitis neurologic impairment was observed in three patients, of whom two siblings had Dyke–Davidoff–Masson syndrome, and an additional distantly related patient suffered from cerebral infarction. Our report adds to the previously reported POU1F1 gene variants causing CPHD and emphasises the importance of genetic testing in countries with high rates of consanguineous marriage such as Sudan. Genetic diagnostics elucidated that the aetiologies of hypopituitarism and brain abnormalities, identified in a subset of affected members, were separate. Additionally, as central hypocortisolism is not characteristic of POU1F1 deficiency, hydrocortisone replacement therapy could be discontinued. Elucidation of a genetic cause, therefore, contributed to the more rational clinical management of hypopituitarism in affected family members.

Congenital hypopituitarism due to novel compound heterozygous POU1F1 gene mutation: A case report and review of the literature

Failure to thrive is one of the most common complaints in the endocrinology and genetics clinic. An 8-month-old girl with presentation of motor developmental delay, failure to thrive, and midline facial defects, with history of hypoglycemia at birth and central congenital hypothyroidism (CCH), was brought to our genetic clinic. Hormone test demonstrated combined pituitary hormone deficiency with growth hormone deficiency (GHD), central hypothyroidism, and hypoprolactinemia. Brain magnetic resonance imaging (MRI) showed anterior pituitary hypoplasia (APH), abnormal pituitary stalk, and preserved posterior pituitary lobe. Whole exome sequence (WES) identified a compound heterozygous mutation of the POU1F1 gene: c.649C>T (p.Arg217Ter) and c.662T>C (p.Ile221Thr), which are de novo mutation and inherited from mother, respectively. The patient's phenotype was consistent clinically with congenital hypopituitarism due to the POU1F1 gene mutation. Based on our literature review, this is the first report of the c.662T>C mutation, to the best of our knowledge. Our study demonstrates the power of WES for early diagnosis of congenital hypopituitarism with its relative phenotype for improving prognosis and preventing irreversible deficit.

Genetic spectrum and predictors of mutations in four known genes in Asian Indian patients with growth hormone deficiency and orthotopic posterior pituitary: an emphasis on regional genetic diversity

CONTEXT

Regional variation in prevalence of genetic mutations in growth hormone deficiency (GHD) is known.

AIM

Study phenotype and prevalence of mutations in GH1, GHRHR, POU1F1, PROP1 genes in GHD cohort.

METHODS

One hundred and two patients {Isolated GHD (IGHD): 79; combined pituitary hormone deficiency (CPHD): 23} with orthotopic posterior pituitary were included. Auxologic, hormonal and radiological details were studied. All four genes were analysed in IGHD patients. POU1F1 and PROP1 were studied in CPHD patients.

RESULTS

Of 102, 19.6% were familial cases. Height SDS, mean (SD) was - 5.14 (1.63). Peak GH, median (range) was 0.47 ng/ml (0-6.59), 72.5% patients had anterior pituitary hypoplasia (APH). Twenty mutations (novel: 11) were found in 43.1% patients (n = 44, IGHD-36, CPHD-8). GHRHR mutations (n = 32, p.Glu72* = 24) were more common than GH1 mutations (n = 4) in IGHD cohort. POU1F1 mutations (n = 6) were more common than PROP1 mutations (n = 2) in CPHD cohort. With few exceptions, this prevalence pattern is contrary to most studies in world-literature. No patients with peak GH > 4 ng/ml had mutations, signifying it as negative predictor. While many parameters were significant on univariate analysis, only positive family history and lower median peak GH levels were significant predictors of mutations on multivariate analysis in IGHD patients.

CONCLUSION

At variance with world literature, we found reverse predominance of GHRHR over GH1 mutations, POU1F1 over PROP1 mutations and predominance of GHRHR p.Glu72* mutations thus re-affirming the regional diversity in GHD genetics. We report positive and negative predictors of mutations in GHD.

Mutations Within the Transcription Factor PROP1 in a Cohort of Turkish Patients with Combined Pituitary Hormone Deficiency

OBJECTIVE

Mutations of the genes encoding transcription factors which play important roles in pituitary morphogenesis, differentiation and maturation may lead to combined pituitary hormone deficiency (CPHD). PROP1 gene mutations are reported as the most frequent genetic aetiology of CHPD. The aim of this study was to describe the phenotypes of Turkish CPHD patients and define the frequency of PROP1 mutations.

METHODS

Fifty-seven CPHD patients from 50 families were screened for PROP1 mutations. The patients were affected by growth hormone (GH) and additional anterior pituitary hormone deficiencies.

RESULTS

All patients had GH deficiency. In addition, 98.2% had central hypothyroidism, 45.6% had hypogonadotropic hypogonadism, 43.8% had adrenocorticotropic hormone deficiency and 7.1% had prolactin deficiency. Parental consanguinity rate was 50.9% and 14 cases were familial. Mean height standard deviation score (SDS) and weight SDS were -3.8±1.4 and -3.1±2.0, respectively. Of 53 patients with available pituitary imaging, 32 (60.4%) showed abnormalities. None had extra-pituitary abnormalities. Eight index patients had PROP1 gene mutations. Five sporadic patients were homozygous for c.301_302delAG (p.Leu102CysfsTer8) mutation, two siblings had exon 2 deletion, two siblings had complete gene deletion and two siblings were homozygous for the novel c.353A>G (p.Q118R) mutation. The frequency of the PROP1 mutations was 16% in our cohort. Mutation rate was significantly higher in familial cases compared to sporadic cases (42.8% vs 11.6%; p<0.01).

CONCLUSION

Phenotype of patients regarding hormonal deficiencies, pituitary morphology, presence of extra-pituitary findings, family history of CPHD and parental consanguinity are important for deciding which pituitary transcription factor deficiency should be investigated. PROP1 mutation frequencies vary in different populations and its prevalence is high in Turkish CPHD patients.

Hypopituitarism in five PROP1 mutation siblings: long-lasting natural course and the effects of growth hormone replacement introduction in middle adulthood

Twenty years after the first description of combined hypopituitarism (CPHD) caused by PROP1 mutations, the phenotype of affected subjects is still challenging for clinicians. These patients suffer from pituitary hormone deficits ranging from IGHD to panhypopituitarism. ACTH deficiency usually develops later in life. Pituitary size is variable. PROP1 mutation is the most frequent in familial congenital hypopituitarism (CH). Reports on initiation of hormonal replacement including growth hormone (GH) in adults with CH are scarce. We identified 5 adult siblings with CPHD due to PROP1 mutation (301-302delAG), aged 36-51 years (4 females), never treated for hormone deficiencies. They presented with short stature (SD from - 3.7 to - 4.7), infantile sexual characteristic, moderate abdominal obesity and low bone mineral density in 3 of them. Complete hypopituituitarism was confirmed in three siblings, while two remaining demonstrated GH, TSH, FSH and LH deficiencies. Required hormonal replacement including rhGH was initiated in all patients. After several months necessity for hydrocortisone replacement developed in all patients. After 2 years of continual replacement therapy, BMD and body composition (measured by DXA-dual X-ray absorptiometry) improved in all subjects, most prominently in two younger females and the male sibling. Besides rhGH therapy, these three patients have received sex hormones contributing to the favorable effect. The male sibling was diagnosed with brain glioblastoma two years following complete hormonal replacement. This report provides important experience regarding hormonal replacement, particularly rhGH treatment, in adults with long-term untreated CH. Beneficial effect of such therapy are widely acknowledged, yet these subjects could be susceptible to certain risks of hormonal treatment initiated in adulthood. Careful and continual clinical follow-up is thus strongly advised.

Genetic Anomalies of Growth Hormone Deficiency in Pediatrics

Several different proteins regulate, directly or indirectly, the production of growth hormones from the pituitary gland, thereby complex genetics is involved. Defects in these genes are related to the deficiency of growth hormones solely, or deficiency of other hormones, secreted from the pituitary gland including growth hormones. These studies can aid clinicians to trace the pattern of the disease between the families, start early treatment and predict possible future consequences. This paper highlights some of the most common and novel genetic anomalies concerning growth hormones, which are responsible for various genetic defects in isolated growth and combined pituitary hormone deficiency disease.

Clinical evaluation of pituitary insufficiency in adult population

Background/aim

This retrospective study aimed to investigate the clinical profile of pituitary insufficiency (PI) in adult population.

Materials and methods

One hundred and fifty patients who were diagnosed as having PI between 2012 and 2018 (53.3% female, mean age 48.13 ± 15.83 years) were retrospectively analyzed.

Results

Age at diagnosis was higher in females as compared with males (51.13 ± 15.95 vs. 44.70 ± 15.08 years, P = 0.012). The most frequent presenting signs were headache (29.4%) and visual disturbance (19.6%) in general. Females frequently presented with headache (33.3%), whereas males presented with sexual dysfunction (34.4%). The most frequent cause of PI was nonfunctional pituitary adenoma (28.8%) in general population. A frequent cause of PI was Sheehan’s syndrome (33.8%) among females and nonfunctional pituitary adenoma (38.6%) among males. Pituitary macroadenoma (75.8%) was frequent in pituitary tumors with PI. 55.3 % of the patients had 4 pituitary hormones deficiencies and 26.0% of patients had 3 pituitary hormones deficiencies. Gonadotropin deficiency was the leading pituitary hormone deficiency. The frequency of posttraumatic PI was 4.7% in the general population.

Conclusion

Nonfunctional pituitary adenoma was the most common cause of PI among males and Sheehan’s syndrome was a major etiologic factor in females. Sheehan’s syndrome remains an important health problem in Turkey although obstetric care has improved. Posttraumatic PI should be considered in the differential diagnosis of idiopathic PI.

Development of the Pituitary Gland

The development of the anterior pituitary gland occurs in distinct sequential developmental steps, leading to the formation of a complex organ containing five different cell types secreting six different hormones. During this process, the temporal and spatial expression of a cascade of signaling molecules and transcription factors plays a crucial role in organ commitment, cell proliferation, patterning, and terminal differentiation. The morphogenesis of the gland and the emergence of distinct cell types from a common primordium are governed by complex regulatory networks involving transcription factors and signaling molecules that may be either intrinsic to the developing pituitary or extrinsic, originating from the ventral diencephalon, the oral ectoderm, and the surrounding mesenchyme. Endocrine cells of the pituitary gland are organized into structural and functional networks that contribute to the coordinated response of endocrine cells to stimuli; these cellular networks are formed during embryonic development and are maintained or may be modified in adulthood, contributing to the plasticity of the gland. Abnormalities in any of the steps of pituitary development may lead to congenital hypopituitarism that includes a spectrum of disorders from isolated to combined hormone deficiencies including syndromic disorders such as septo-optic dysplasia. Over the past decade, the acceleration of next-generation sequencing has allowed for rapid analysis of the patient genome to identify novel mutations and novel candidate genes associated with hypothalmo-pituitary development. Subsequent functional analysis using patient fibroblast cells, and the generation of stem cells derived from patient cells, is fast replacing the need for animal models while providing a more physiologically relevant characterization of novel mutations. Furthermore, CRISPR-Cas9 as the method for gene editing is replacing previous laborious and time-consuming gene editing methods that were commonly used, thus yielding knockout cell lines in a fraction of the time. © 2020 American Physiological Society. Compr Physiol 10:389-413, 2020.

Combined pituitary hormone deficiency caused by PROP1 mutations: update 20 years post-discovery

The first description of patients with combined pituitary hormone deficiencies (CPHD) caused by PROP1 mutations was made 20 years ago. Here we updated the clinical and genetic characteristics of patients with PROP1 mutations and summarized the phenotypes of 14 patients with 7 different pathogenic PROP1 mutations followed at the Hospital das Clínicas of the University of Sao Paulo. In addition to deficiencies in GH, TSH, PRL and gonadotropins some patients develop late ACTH deficiency. Therefore, patients with PROP1 mutations require permanent surveillance. On magnetic resonance imaging, the pituitary stalk is normal, and the posterior lobe is in the normal position. The anterior lobe in patients with PROP1 mutations is usually hypoplastic but may be normal or even enlarged. Bi-allelic PROP1 mutations are currently the most frequently recognized genetic cause of CPHD worldwide. PROP1 defects occur more frequently among offspring of consanguineous parents and familial cases, but they also occur in sporadic cases, especially in countries in which the prevalence of PROP1 mutations is relatively high. We classified all reported PROP1 variants described to date according to the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG-AMP) guidelines: 29 were pathogenic, 2 were likely pathogenic, and 2 were of unknown significance. An expansion of the phenotype of patients with PROP1 mutations was observed since the first description 20 years ago: variable anterior pituitary size, different pathogenic mutations, and late development of ACTH deficiency. PROP1 mutations are the most common cause of autosomal recessive CPHD with a topic posterior pituitary lobe. Arch Endocrinol Metab. 2019;63(2):167-74.

Precocious or early puberty in patients with combined pituitary hormone deficiency due to POU1F1 gene mutation: case report and review of possible mechanisms

Central precocious puberty (CPP) or early puberty (EP) is a rare entity in combined pituitary hormone deficiency (CPHD), the latter caused by mutations in pituitary transcription factor genes. The early onset of puberty in two patients with CPHD with POU1F1 gene mutation was evaluated. A 3-month-old boy was diagnosed with central hypothyroidism, and L-thyroxine was commenced. He was referred for the evaluation of short stature at 20 months of age. Anthropometric evaluation revealed severe short stature (- 6.1 SDS), and growth hormone (GH) and prolactin deficiencies were diagnosed. Homozygous POU1F1 gene mutation (c.731T>G, p. I244S) was also detected. Testicular enlargement and high luteinizing hormone (LH) levels were observed at 7 years and 9 months of age while he was on GH and L-thyroxine treatment. Due to rapid progression of puberty, gonadotropin-releasing hormone analogue (GnRHa) was initiated at 11.3 years of age. This patient recently turned 19.2 years old, and his final height was - 2.3 SDS. The second patient, a 6-month-old boy, was also referred for growth retardation. His height was - 2.7 SDS, and GH and thyroid-stimulating hormone (TSH) deficiencies were diagnosed. He also had homozygous (c.10C>T, p.Q4*) POU1F1 gene mutation. Onset of puberty was relatively early, at 10 years, with advanced bone age. He was on GnRHa treatment between 11.5 and 12.5 years of age. Recent evaluation of the patient was at 13.6 years of age, and he is still on levothyroxine and GH treatment. The relationship between the POU1F1 genotype and CPP or EP has not as yet been firmly established in humans. Animal studies have revealed that the Pou1f1 gene has a major effect on regulation of GnRH receptor function and the Gata2 gene. It has also been demonstrated that this gene controls gonadotrope evolution and prevents excess gonadotropin levels. Further studies are, however, needed to elucidate the relation between POU1F1 function and CPP.

Genetic screening of regulatory regions of pituitary transcription factors in patients with idiopathic pituitary hormone deficiencies

PURPOSE

Mutation frequencies of PROP1, POU1F1 and HESX1 in patients with combined pituitary hormone deficiencies (CPHD) vary substantially between populations. They are low in sporadic CPHD patients in Western Europe. However, most clinicians still routinely send DNA of their CPHD patients for genetic screening of these pituitary transcription factors. Before we can recommend against screening of PROP1, POU1F1 and HESX1 as part of routine work-up for Western-European sporadic CPHD patients, it is crucial to rule out possible defects in regulatory regions of these genes, which could also disturb the complex process of pituitary organogenesis.

METHODS

The regulatory regions of PROP1, POU1F1 and HESX1 are not covered by Whole Exome Sequencing as they are largely located outside the coding regions. Therefore, we manually sequenced the regulatory regions, previously defined in the literature, of PROP1, POU1F1 and HESX1 among 88 Dutch patients with CPHD. We studied promoter SNPs in relation to phenotypic data.

RESULTS

We found six known SNPs in the PROP1 promoter. In the POU1F1 promoter, we found one new variant and two known SNPs. We did not find any variant in the HESX1 promoter.

CONCLUSION

Although the new POU1F1 variant might explain the phenotype of one patient, the general conclusion of this study is that variants in regulatory regions of PROP1, POU1F1 and HESX1 are rare in patients with sporadic CPHD in the Netherlands. We recommend that genetic screening of these pituitary transcription factors should no longer be part of routine work-up for Western-European, and especially Dutch, sporadic CPHD patients.

Molecular analysis of brazilian patients with combined pituitary hormone deficiency and orthotopic posterior pituitary lobe reveals eight different PROP1 alterations with three novel mutations

BACKGROUND

Mutations in PROP1, HESX1 and LHX3 are associated with combined pituitary hormone deficiency (CPHD) and orthotopic posterior pituitary lobe (OPP).

OBJECTIVE

To identify mutations in PROP1, HESX1 and LHX3 in a large cohort of patients with CPHD and OPP (35 Brazilian, two Argentinian).

DESIGN AND METHODS

We studied 23 index patients with CPHD and OPP (six familial and 17 sporadic) as well as 14 relatives. PROP1 was sequenced by the Sanger method in all except one sporadic case studied using a candidate gene panel. Multiplex ligation-dependent probe amplification (MLPA) was applied to one familial case in whom PROP1 failed to amplify by PCR. In the 13 patients without PROP1 mutations, HESX1 and LHX3 were sequenced by the Sanger method.

RESULTS

We identified PROP1 mutations in 10 index cases. Three mutations were novel: one affecting the initiation codon (c.1A>G) and two affecting splicing sites, c.109+1G>A and c.342+1G>C. The known mutations, c.150delA (p.Arg53Aspfs*112), c.218G>A (p.Arg73His), c.263T>C (p.Phe88Ser) and c.301_302delAG (p.Leu102Cysfs*8), were also detected. MLPA confirmed complete PROP1 deletion in one family. We did not identify HESX1 and LHX3 mutations by Sanger.

CONCLUSION

PROP1 mutations are a prevalent cause of congenital CPHD with OPP, and therefore, PROP1 sequencing must be the first step of molecular investigation in patients with CPHD and OPP, especially in populations with a high frequency of PROP1 mutations. In the absence of mutations, massively parallel sequencing is a promising approach. The high prevalence and diversity of PROP1 mutations is associated with the ethnic background of this cohort.

Rare Frequency of Mutations in Pituitary Transcription Factor Genes in Combined Pituitary Hormone or Isolated Growth Hormone Deficiencies in Korea

PURPOSE

Congenital hypopituitarism is caused by mutations in pituitary transcription factors involved in the development of the hypothalamic-pituitary axis. Mutation frequencies of genes involved in congenital hypopituitarism are extremely low and vary substantially between ethnicities. This study was undertaken to compare the clinical, endocrinological, and radiological features of patients with an isolated growth hormone deficiency (IGHD) or combined pituitary hormone deficiency (CPHD).

MATERIALS AND METHODS

This study included 27 patients with sporadic IGHD and CPHD. A mutation analysis of the POU1F1, PROP1, LHX3, LHX4, and HESX1 genes was performed using genomic DNA from peripheral blood leukocytes.

RESULTS

IGHD and CPHD were observed in 4 and 23 patients, respectively. Mean age at diagnosis was 8.28±7.25 years for IGHD and 13.48±10.46 years for CPHD (p=0.37). Serum insulin-like growth factor-1 and peak growth hormone (GH) levels following GH stimulation tests were significantly lower in patients with CPHD than in those with IGHD (p<0.05). Sellar MRI findings revealed structural abnormalities in 3 patients with IGHD (75%) and 21 patients with CPHD (91.3%) (p=0.62). A mutation analysis identified homozygous p.R109Q mutations in HESX1 in a patient with CPHD. Patients with CPHD had more severe GHD than those with IGHD.

CONCLUSION

The frequency of defects in the genes encoding pituitary transcription factors was extremely low in Korean patients with congenital hypopituitarism. Environmental factors and the impact of other causative genes may contribute to this clinical phenotype.

Combined pituitary hormone deficiency due to gross deletions in the POU1F1 (PIT-1) and PROP1 genes

Pituitary development depends on a complex cascade of interacting transcription factors and signaling molecules. Lesions in this cascade lead to isolated or combined pituitary hormone deficiency (CPHD). The aim of this study was to identify copy number variants (CNVs) in genes known to cause CPHD and to determine their structure. We analyzed 70 CPHD patients from 64 families. Deletions were found in three Turkish families and one family from northern Iraq. In one family we identified a 4.96 kb deletion that comprises the first two exons of POU1F1. In three families a homozygous 15.9 kb deletion including complete PROP1 was discovered. Breakpoints map within highly homologous AluY sequences. Haplotype analysis revealed a shared haplotype of 350 kb among PROP1 deletion carriers. For the first time we were able to assign the boundaries of a previously reported PROP1 deletion. This gross deletion shows strong evidence to originate from a common ancestor in patients with Kurdish descent. No CNVs within LHX3, LHX4, HESX1, GH1 and GHRHR were found. Our data prove multiplex ligation-dependent probe amplification to be a valuable tool for the detection of CNVs as cause of pituitary insufficiencies and should be considered as an analytical method particularly in Kurdish patients.

Genetics of Combined Pituitary Hormone Deficiency: Roadmap into the Genome Era

The genetic basis for combined pituitary hormone deficiency (CPHD) is complex, involving 30 genes in a variety of syndromic and nonsyndromic presentations. Molecular diagnosis of this disorder is valuable for predicting disease progression, avoiding unnecessary surgery, and family planning. We expect that the application of high throughput sequencing will uncover additional contributing genes and eventually become a valuable tool for molecular diagnosis. For example, in the last 3 years, six new genes have been implicated in CPHD using whole-exome sequencing. In this review, we present a historical perspective on gene discovery for CPHD and predict approaches that may facilitate future gene identification projects conducted by clinicians and basic scientists. Guidelines for systematic reporting of genetic variants and assigning causality are emerging. We apply these guidelines retrospectively to reports of the genetic basis of CPHD and summarize modes of inheritance and penetrance for each of the known genes. In recent years, there have been great improvements in databases of genetic information for diverse populations. Some issues remain that make molecular diagnosis challenging in some cases. These include the inherent genetic complexity of this disorder, technical challenges like uneven coverage, differing results from variant calling and interpretation pipelines, the number of tolerated genetic alterations, and imperfect methods for predicting pathogenicity. We discuss approaches for future research in the genetics of CPHD.

HESX1 mutations in patients with congenital hypopituitarism: variable phenotypes with the same genotype

INTRODUCTION

Mutations in the transcription factor HESX1 can cause isolated growth hormone deficiency (IGHD) or combined pituitary hormone deficiency (CPHD) with or without septo-optic dysplasia (SOD). So far there is no clear genotype-phenotype correlation.

PATIENTS AND RESULTS

We report four different recessive loss-of-function mutations in three unrelated families with CPHD and no midline defects or SOD. A homozygous p.R160C mutation was found by Sanger sequencing in two siblings from a consanguineous family. These patients presented with ACTH, TSH and GH deficiencies, severe anterior pituitary hypoplasia (APH) or pituitary aplasia (PA) and normal posterior pituitary. The p.R160C mutation was previously reported in a case with SOD, CPHD and ectopic posterior pituitary (EPP). Using exome sequencing, a homozygous p.I26T mutation was found in a Brazilian patient born to consanguineous parents. This patient had evolving CPHD, normal ACTH, APH and normal posterior pituitary (NPP). A previously reported patient homozygous for p.I26T had evolving CPHD and EPP. Finally, we identified compound heterozygous mutations in HESX1, p.[R159W];[R160H], in a patient with PA and CPHD. We showed that both of these mutations abrogate the ability of HESX1 to repress PROP1-mediated transcriptional activation. A patient homozygous for p.R160H was previously reported in a patient with CPHD, EPP, APH.

CONCLUSION

These three examples demonstrate that HESX1 mutations cause variable clinical features in patients, which suggests an influence of modifier genes or environmental factors on the phenotype.